Los Angeles Fire Department spokesman Shawn Lenske said nine of the injured were taken to hospitals and the other four, including the truck driver, were treated at the scene.
Metrolink spokesman Jeff Lustgarten said the train was headed south from Lancaster toward Union Station in downtown Los Angeles when the collision occurred shortly before 2:30 p.m PDT, the Los Angeles Times reported.
"The gates were functioning, but why the truck was on the tracks at the time, I don't know," he said.
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